Why are some bird eggs darker in colour than others? It’s true that bird eggs come in an array of colours. From previous research on tropical birds, we know that darker hues help in camouflaging- it is harder for predators to spot. Also, darker pigments have molecules that protect against ultra-violet rays and infections. But what about the colder climes? A recently published global study says that the brightness and colour of eggshells are closely correlated with the temperature of a region. More birds up in the cold north lay darker eggs and the reason is different- darker pigments absorb more heat, keeping the chicks warm!